Measuring "unaligned" angles?

How can I measure the angle between the line and the plane? (At the point where the angle is greatest)

In my attachment, there’s 2 examples. In the second , I’ve drawn a couple of helping lines. In this case I only need to find the angle of the triangle. But also this isn’t as straight forward as it seems.

One possibility I’ve found is to rotate the triangle to align it with either top or right view, then I can make a measurement, but ideally I 'd like to know how to measure this without rotating the piece, as it is part of a bigger model.

Thanks in advance,

unaligned.3dm (164.0 KB)

I would probably rotate it to align with a view point. When you rotate make a copy, leaving your original in place. That way you are not messing up your drawing or struggling to rotate it back. Also you can project your line onto the plane, thus giving Rhino what it needs to measure an angle.
Good luck,

Another way:

  • Run Intersect to intersect the line and the plane (makes a point)
  • Run Line/Normal and run a line normal to the plane some arbitrary distance from the intersection point
  • Measure the angle with the Angle tool

And in Rhino V6 in any case, you can simply use the Angle command with the TwoObjects option to measure the angle between a line and a plane.

How are you measuring the angle? If you use the Angle command there is no need to align anything with a C-Plane. You can use the Angle command with the TwoObject option to measure the angle between a line and plane directly wihout creating any other geometry. The angle measure is the included angle between the plane and the line; ie it will be 0 degrees if the line is parallel to the plane and 90 degrees if the line is perpendicular to the plane. For the angle between the line and the normal to the plane subtract the result of the Angle command from 90 degrees.

Thanks again for your feedback. I thought I was missing something obvious here, at least it doesn’t seem so straightforward to measure an angle like this.

The Angle TwoObject method seems to work in Rhino V5 also. So I’ll be using that in the future. However this doesn’t any dimension arrows on the drawing itself, only a command line output. But I can live with that :slight_smile:

Yes, that’s correct, these are measurement tools, not dimensioning tools. (I often see people placing dimensions just as measurement tool because they don’t know that a measurement tool exists)

However, actual dimension objects in Rhino are a different animal, they are planar 2D objects that need to have a specified plane to lie in. For your line-to-plane example, the plane in which the dimension should lie would need to be calculated, and Rhino does not know how to do that automatically… I think it could be scripted though. The angle that is getting measured in this case appears to be between the line and its projection on the plane in the direction of the plane normal; those two lines form a plane on which a dimension object could be placed.

Thanks everyone, I learned a new command, explained in a very clear way. You have got to love this forum.


How do I measure the angle between the lines which are situated in different planes.

PseudoSteinerTrees2Rhino5 (1).gh (13.1 KB)

Hello - two lines that meet are in the same plane so you can always set a plane - say using the end points - and measure in that plane.


Hi Pascal,

Kindly guide.


Hi Aya - something like this, I suppose:

The line direction should be away from the common endpoint.


Hi Pascal,

With your help I am able to measure the angle between two lines.Is there a way I can measure all the angles between the lines taken as a list, as you can see I have a branch of lines which increases with the count, so measuring all the angles one by one would be impossible.


Using the topologizer component from here: (10.6 KB)

1 Like

Splendid Daniel.
Thank you so much.
Your component works great :slight_smile:

Thank you for your swift reply

Hello all,
Why am I getting an error in Topologizer and fattener.
I tried changing the tolerances still no change.
Hence I am not able to measure the angle.

The file is in meters.

Topologizer (20.8 KB)

Thank you for your time in advance.topo error.3dm (70.5 KB)